Observational learning is important for citizen, or particularly for young kids to have more interest in the cosmology and astronomy, and to study scientific approach on them. That learning experience does not only mean a passive experience like astronomy observation through naked eyes with listening to a commentary, but it also include detailed observation of dark stars that are unable to be observed with naked eyes through binoculars or astronomical telescope, and further include photographic observation of dark celestial objects that are unable to be observed even through an astronomical telescopes and those emitting light of wavelengths that are unable to be observed with naked eyes. These experiences will lead the citizen to advanced studies.
For those purposes, educational facilities hold events for astronomy observation with astronomical telescopes or cameras. However, the events have not been able to provide high-quality experiences of observation of a starry sky for the following reasons.    1. The sky on city side is too bright with city lights for observation of dark stars. The observation must be conducted under a dark sky.    2. The observation condition is restrictive because the observation condition is affected by the place, season, and the time. Thus, celestial objects that can be observed in the events are limited.    3. The stars can not be observed on bad weather.
Under these circumstances, projection planetariums and various types of starry sky reproducing devices to reproduce stars directly have been proposed. With these items, promoters of the events can produce high-quality astronomy observations even on daytime, or on bad weather.
The starry sky reproducing devices as disclosed in Patent Literatures 1 and 2 have been used widely as planetariums. A star projection device, settled near the center in the dome-shaped structure having a white screen inside, can project stars under the condition the inside of the dome is dark. Dark celestial objects that can not be reproduced by the star projection device are projected by a general-purpose projector, instead. Thus, observers in the dome can observe an artificial starry sky.
The starry sky reproducing devices disclosed in Patent Literatures 3 to 6 use the method to form star images directly on the surface of a dome-shaped structure. The one in Patent Literature 3 is made of a sheet of paper having an aluminum foil thereon. It has holes on the surface of the sheet, so that an observer can observe starlit by holding up the sheet in front of a background light like such as from a TV set. Moreover, the one in Patent Literature 4 has the starlit wallpaper on which a starry sky is drawn with luminous paints. The one in Patent Literature 5 has light emitting-elements like LEDs inside a dome-shaped structure and the elements reproduce starts.
The starry sky reproducing device in Patent Literature 6 has optical fibers. The edges of the fibers are fixed on the wall of a dome. An observer can observe light led by the fibers as stars.